JP2017010280A - Tire pattern model creation method and tire simulation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To generate mesh and shorten time of obtaining a model based on the set of elements divided by the mesh.SOLUTION: A land part being a portion of a tire tread surface is divided into a first area making any one surface penetrate in the first direction perpendicular to the one surface and a second area being a portion other than the first area. The mesh on the one surface is moved to the first direction and the first area is divided into multiple, and thereby the mesh is generated about the first area and a three-dimensional model of the first area is generated. The mesh on the cut surface of the second area is moved to the second direction unlike the first direction and the second area is divided into multiple, and thereby the mesh about the second area is generated to generate the three-dimensional model of the second area. The three-dimensional model generated about the first area is combined with the three-dimensional model generated about the second area.SELECTED DRAWING: Figure 12

Description

  The present invention relates to a tire pattern model creation method and a tire simulation method.

  Since the tread pattern has a great influence on the durability performance of the tire, the hydroplaning performance of the tire, the wear performance of the tire, or the cornering performance, the tread pattern needs to be modeled as faithfully as possible.

  In order to perform structural analysis or fluid analysis by the finite element method or the finite volume method, it is necessary to represent the shape of the analysis target as a set of simple elements that are simple in shape and can be calculated by a computer. A collection of small elements is called a mesh. By generating a mesh for the analysis target and modeling it as a set of elements divided by the mesh, the shape of the analysis target can be calculated by a computer.

  Since the tread pattern of a tire has a great influence on the hydroplaning performance, tire wear performance, or cornering performance of the tire, it is necessary to model the tread pattern as faithfully as possible. Patent Document 1 discloses a method of creating a finite element model for a tire in which a tread portion has an uneven shape.

JP 2006-18422 A

  There are cases where the mesh is manually generated while looking at the display content of the screen of CAD (Computer Aided Design) software, and where the mesh is automatically generated by the function of the CAD software. By automatically generating the mesh, the work time can be shortened. When a mesh is generated for a tire and a set of elements divided by the mesh is obtained, a mesh having a complicated shape cannot be automatically generated and may be generated manually. When the mesh is manually generated, the work time is longer than when the mesh is automatically generated.

  The present invention has been made in view of the above, and provides a tire pattern model creation method capable of shortening the time for generating a mesh and obtaining a model based on a set of elements divided by the mesh, and a tire simulation method using the tire pattern model creation method The purpose is to do.

  In order to solve the above-described problems and achieve the object, a tire pattern model creation method according to an aspect includes a first portion in which any one surface is orthogonal to the one surface with respect to a land portion that is a part of a tire tread surface. Dividing into a first region penetrating in a direction and a second region which is a portion other than the first region, and moving the mesh on the one surface in the first direction to A step of generating a mesh for the first region by dividing the first region to generate a three-dimensional model of the first region, and a mesh for a cut surface of the second region different from the first direction. Generating a mesh for the second region by moving in the direction of 2 to divide the second region into a plurality of regions, and generating a three-dimensional model of the second region; Including 3-dimensional model and the step of combining the three-dimensional model generated for the second region. According to this method, it is possible to reduce the time for generating a mesh and obtaining a model based on a set of elements divided by the mesh.

  When generating a three-dimensional model of the second region, when the groove wall angle formed between the side surface of the first region and the wall surface of the second region changes, the second region is divided into portions where the groove wall angle is the same. And generating a three-dimensional model by generating a mesh for the second region while moving the cutting plane in the second direction for each of the divided portions, and combining the three-dimensional models of the individual groove wall partial regions Thus, it is preferable to generate a three-dimensional model of the second region. By dividing the second region into a plurality of partial regions, even a complex region where the curved surfaces of the groove bottom intersect can be generated automatically instead of manually, so a model based on a set of elements divided by the mesh can be created. The time to obtain can be shortened.

  When dividing the land portion into the first region and the second region, a representative position of the groove wall angle is set, and at least one element is separated from the representative position in the inward direction of the land portion. It is preferable to set a position and divide the first area and the second area along the corresponding position. Thereby, even when it is difficult to move the cut surface along the contour of the land portion because the groove wall angle is zero, the second region is cut by providing a thickness of one or more elements. Surface elements can be generated.

  When combining the three-dimensional model generated for the first region and the three-dimensional model generated for the second region, the meshes of the first region and the second region are matched so that the shapes of the meshes of adjacent regions match. It is preferable to produce. If a mesh is created in this way, node sharing between each region boundary can be used, so that setting work such as constraint coupling is not required, and the efficiency of creating an analysis model can be further improved.

  In order to solve the above-described problems and achieve the object, a tire simulation method according to one aspect includes a step of creating a tire pattern model by the tire pattern model creation method, and a three-dimensional model of a portion other than the tire pattern model A step of creating a casing model, a step of integrating the tire pattern model and the casing model, and a step of performing a simulation on a model of the entire tire integrating the tire pattern model and the casing model. Including. According to this method, it is possible to reduce the time required to generate a mesh and obtain a model based on a set of elements divided by the mesh, and the time required for simulation can be reduced.

  According to one embodiment of the present invention, the time for generating a mesh and obtaining a model based on a set of elements divided by the mesh can be reduced.

FIG. 1 is a cross-sectional view in the tire meridian direction showing the pneumatic tire according to the first embodiment. FIG. 2 is an explanatory diagram illustrating an analysis apparatus that executes the tire simulation method according to the present embodiment. FIG. 3A is a diagram for explaining a land region and a groove wall region. FIG. 3B is a diagram for explaining a land region and a groove wall region. FIG. 3C is a diagram illustrating the land region and the groove wall region. FIG. 3D is a diagram illustrating a case where the surface element is moved in the tire radial direction without changing the size of the surface element. FIG. 3E is a diagram showing a case of moving in the tire radial direction while changing the size of the surface element. FIG. 4A is a diagram illustrating a relationship between a surface element in a land region and a cut surface element in a groove wall region. FIG. 4B is a diagram illustrating an example of a mesh generated for a land portion. FIG. 4C is a diagram illustrating an example of a model related to the entire tire. FIG. 5 is a flowchart showing a tire pattern model creation method according to the first embodiment. FIG. 6 is a diagram illustrating an example of dividing the groove wall region and the land portion region. FIG. 7A is a diagram illustrating another example of dividing the groove wall region and the land portion region. FIG. 7B is a diagram illustrating another example of dividing the groove wall region and the land portion region. FIG. 8 is a diagram for explaining a tire pattern model creation method according to the second embodiment. FIG. 9 is a diagram illustrating an example of a cut surface element at each representative position. FIG. 10 is a diagram illustrating an example of a model of a groove wall region obtained by moving each cutting plane element at each representative position. FIG. 11 is a diagram for explaining representative positions. FIG. 12 is a diagram illustrating an example of a land portion model obtained by the second embodiment. FIG. 13 is a flowchart showing a tire pattern model creation method according to the second embodiment. FIG. 14A is a diagram illustrating a tire pattern model creation method according to the third embodiment. FIG. 14B is a diagram illustrating an example of a cut surface element having a thickness. FIG. 14C is a diagram illustrating an example of a land portion excluding the cut surface element illustrated in FIG. 14B. FIG. 15 is a flowchart showing a tire pattern model creation method according to the third embodiment. FIG. 16A is a diagram for explaining a method of creating a model of the entire tire by integrating the pattern model and the casing model. FIG. 16B is a diagram illustrating a method of creating a model of the entire tire by integrating the pattern model and the casing model. FIG. 17 is a flowchart illustrating an example of a method for creating and simulating a model of the entire tire. FIG. 18 is a diagram illustrating an example of a tire pattern analysis model.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. Further, the constituent elements of this embodiment include those that can be replaced while maintaining the identity of the invention and that are obvious for replacement. In addition, a plurality of modifications described in this embodiment can be arbitrarily combined within a range obvious to those skilled in the art.

(First embodiment)
Hereinafter, a tire pattern model creation method according to the first embodiment will be described.

  FIG. 1 is a cross-sectional view in the tire meridian direction showing the pneumatic tire according to the first embodiment. In the following description, the tire radial direction refers to a direction orthogonal to the rotation axis (not shown) of the pneumatic tire 1, and the tire radial direction inner side refers to the side toward the rotation axis in the tire radial direction, the tire radial direction outer side. Means the side away from the rotation axis in the tire radial direction. Further, the tire circumferential direction refers to a direction around the rotation axis as a central axis. Further, the tire width direction means a direction parallel to the rotation axis, the inner side in the tire width direction means the side toward the tire equator plane (tire equator line) CL in the tire width direction, and the outer side in the tire width direction means the tire width direction. Is the side away from the tire equatorial plane CL. The tire equatorial plane CL is a plane that is orthogonal to the rotation axis of the pneumatic tire 1 and passes through the center of the tire width of the pneumatic tire 1. The tire width is the width in the tire width direction between the portions located outside in the tire width direction, that is, the distance between the portions farthest from the tire equatorial plane CL in the tire width direction. The tire equator line is a line along the tire circumferential direction of the pneumatic tire 1 on the tire equator plane CL. In the present embodiment, the same sign “CL” as that of the tire equator plane is attached to the tire equator line. In the present embodiment, a case will be described in which the pneumatic tire is a heavy-duty radial tire mounted on a steer shaft such as a truck or bus for long-distance transportation.

  As shown in FIG. 1, the pneumatic tire 1 includes a pair of bead cores 11, a pair of bead fillers 12, a carcass layer 13, a belt layer 14, a tread rubber 15, and a pair of sidewall rubbers 16. . The pair of bead cores 11 has an annular structure and constitutes the cores of the left and right bead portions. The pair of bead fillers 12 includes a lower filler and an upper filler, and is disposed on the tire radial direction outer periphery of the pair of bead cores 11 to reinforce the bead portion. The carcass layer 13 has a single-layer structure and is bridged in a toroidal shape between the left and right bead cores 11 to form a tire skeleton. Further, both end portions of the carcass layer 13 are wound and locked outward in the tire width direction so as to wrap the bead core 11 and the bead filler 12. The belt layer 14 includes a stacked high-angle belt 141, a pair of cross belts 142 and 143, a belt cover 144, and a circumferential reinforcing layer 145, and is disposed on the outer periphery in the tire radial direction of the carcass layer 13.

  Here, the high-angle belt 141 is formed by rolling a plurality of belt cords made of steel or an organic fiber material with a coating rubber, and an absolute value of a belt angle of 40 [deg] or more and 60 [deg] or less. The inclination angle of the fiber direction of the belt cord with respect to the tire circumferential direction). Further, the high-angle belt 141 is laminated and disposed on the outer side in the tire radial direction of the carcass layer 13.

  The pair of cross belts 142 and 143 are formed by rolling a plurality of belt cords made of steel or organic fiber material with a coating rubber, and having a belt angle of 10 [deg] or more and 30 [deg] or less in absolute value. Have. Further, the pair of cross belts 142 and 143 have belt angles with different signs from each other, and are laminated so that the fiber directions of the belt cords cross each other (cross-ply structure). Here, the cross belt 142 located on the inner side in the tire radial direction is called an inner diameter side cross belt, and the cross belt 143 located on the outer side in the tire radial direction is called an outer diameter side cross belt. Note that three or more cross belts may be laminated (not shown). In addition, the pair of cross belts 142 and 143 are disposed so as to be stacked on the outer side in the tire radial direction of the high-angle belt 141.

  The belt cover 144 is formed by coating a plurality of belt cords made of steel or organic fiber material with a coat rubber and rolling, and has a belt angle of 10 [deg] or more and 45 [deg] or less in absolute value. Further, the belt cover 144 is disposed so as to be laminated on the outer side in the tire radial direction of the cross belts 142 and 143. In this embodiment, the belt cover 144 has the same belt angle as the outer diameter side crossing belt 143 and is disposed in the outermost layer of the belt layer 14. The belt layer may further include a circumferential reinforcing layer between the cross belts or on the inner side in the tire radial direction of the cross belt. The circumferential reinforcing layer is made of a steel wire and is configured by winding at least one wire in a spiral shape while inclining within a range of ± 5 [deg] with respect to the tire circumferential direction.

  The circumferential reinforcing layer 145 is made of a steel wire, and is configured by winding at least one wire in a spiral manner while inclining within a range of ± 5 [deg] with respect to the tire circumferential direction. Further, the circumferential reinforcing layer 145 is disposed between the pair of cross belts 142 and 143. Further, the circumferential reinforcing layer 145 is disposed on the inner side in the tire width direction with respect to the left and right edge portions of the pair of cross belts 142 and 143. Specifically, the wire is spirally wound around the outer periphery of the inner diameter side crossing belt 142 to form the circumferential reinforcing layer 145. The circumferential reinforcing layer 145 reinforces the rigidity in the tire circumferential direction, so that the durability performance of the tire is improved.

  The belt layer 14 may have an edge cover (not shown). Generally, the edge cover is formed by rolling a plurality of belt cords made of steel or organic fiber material with a coat rubber, and has a belt angle within a range of ± 5 [deg] with respect to the tire circumferential direction. Further, the edge covers are respectively disposed on the outer sides in the tire radial direction of the left and right edge portions of the outer diameter side cross belt 143 (or the inner diameter side cross belt 142). When these edge covers exhibit a tagging effect, the difference in diameter growth between the tread portion center region and the shoulder region is alleviated, and the uneven wear resistance performance of the tire is improved.

  The tread rubber 15 is disposed on the outer periphery in the tire radial direction of the carcass layer 13 and the belt layer 14 to constitute a tread portion 33 of the tire. The pair of sidewall rubbers 16 are respectively arranged on the outer sides in the tire width direction of the carcass layer 13 to constitute left and right sidewall portions. In this embodiment, the pneumatic tire 1 has a symmetrical structure with the tire equatorial plane CL as the center.

  In the pneumatic tire 1, as shown in FIG. 1, two circumferential main grooves 21 extending in the tire circumferential direction are formed in the tread portion 33. The circumferential main grooves 21 are provided on both sides in the tire width direction across the tire equatorial plane CL. The circumferential main groove 21 extends in a zigzag shape in the circumferential direction.

  A lug groove 60 </ b> A indicated by a broken line is provided between the circumferential main grooves 21. A lug groove 60B is provided from the circumferential main groove 21 toward the outer side in the tire width direction.

  The tread portion 33 has a shape in which the tread rubber 15 is partitioned by the circumferential main groove 21 and is divided into a plurality of land portions, specifically, one land portion 41 and two land portions 42. . The land portion 41 is a region sandwiched between the two circumferential main grooves 21 and the two lug grooves 60A. The two land portions 42 are regions sandwiched between the circumferential main groove 21 and the two lug grooves 60B, respectively. The land portion 42 is an end portion in the tire width direction in a region where the end portion on the outer side in the tire width direction contacts the road surface of the tread portion 33. Here, the tread portion 33 of the pneumatic tire 1 of the present embodiment is asymmetrical with respect to the tire equatorial plane CL as a target plane. Next, an apparatus for executing the tire simulation method according to the present embodiment will be described.

  FIG. 2 is an explanatory diagram illustrating an analysis apparatus that executes the tire simulation method according to the present embodiment. The tire simulation method according to the present embodiment can be realized by the analysis device 50 shown in FIG. The analysis device 50 is a computer and includes a processing unit 52 and a storage unit 54 as shown in FIG. In addition, an input / output device 51 is electrically connected to the analysis device 50. The input / output device 51 has an input unit 53. The input unit 53 inputs physical property values of rubber constituting the tire, physical property values of reinforcing cords, boundary conditions used for deformation analysis such as contact analysis and rolling analysis, and the like to the processing unit 52 and the storage unit 54.

  An input device such as a keyboard or a mouse can be used for the input unit 53. The storage unit 54 stores a computer program including tire analysis (ground contact analysis, rolling analysis, vibration analysis, etc.) and a tire simulation method according to the present embodiment. The storage unit 54 is a non-volatile memory such as a hard disk device, a magneto-optical disk device, or a flash memory (a storage medium that can be read only such as a CD-ROM), or a volatile memory such as a RAM (Random Access Memory). The memory can be configured by a combination of these, or a combination thereof.

  The computer program may be capable of realizing the ground contact analysis, the rolling analysis, or the tire simulation method according to the present embodiment, in combination with a computer program already recorded in the computer system. Here, the “computer system” includes hardware such as an OS (Operating System) and peripheral devices.

  The processing unit 52 includes a model creation unit 52a, a condition setting unit 52b, an analysis unit 52c, an evaluation value calculation unit 52d, and a determination unit 52e. The model creation unit 52 a divides the tire to be analyzed into a plurality of elements having a plurality of nodes, creates a tire model for analysis, and stores the tire model in the storage unit 54. In addition to the tire model, the model creation unit 52a models various members that are determined based on the conditions to be analyzed and the model. For example, in addition to the tire model to be analyzed (tire model), the model creation unit 52a includes a rim model (rim model) that contacts the tire, a wheel model that fits into the tire (wheel model), and a road surface that the tire contacts. Create a model (road surface model). Thereby, the model creation unit 52a creates an analysis model including at least a tire model.

  The condition setting unit 52b sets various conditions for executing the analysis of the analysis model created by the model creation unit 52a. As various conditions, there are a design variable that changes the condition in the analysis result at the time of analysis and a fixed value that does not change the condition. The design variables include the number of belts that make up the tire model belt layer, the position of the belt, the Young's modulus and width of the rubber or coat rubber of the tread of the tire model, the angle of the belt wire, the end and rigidity, the carcass layer Includes at least one of shape and dimensions. In addition to the above, the design variables and fixed values include physical property values of each part constituting the tire model, various shapes and physical property values of models other than the tire model of the analysis model. The condition setting unit 52 b determines various conditions (design variables, fixed values) based on the operation detected by the input unit 53 and the information stored in the storage unit 54. The condition setting unit 52b also sets analysis conditions such as the contents of analysis processing to be executed and analysis convergence conditions. The condition setting unit 52b also sets an area obtained by dividing the surface (profile) of the tire model into a plurality of parts in the tire width direction as the analysis condition. Information on each region obtained by dividing the profile into a plurality of regions is used when the evaluation value is calculated by the evaluation value calculation unit 52d.

  The analysis unit 52c reads the analysis model created by the model creation unit 52a from the storage unit 54, and executes deformation analysis under a predetermined condition. In addition, as a deformation | transformation analysis, the deformation | transformation analysis of the various factor which the created tire model deform | transforms becomes object. Specifically, the analysis unit 52c generates deformation by analyzing deformation generated by bringing the tire into contact with the road surface, analyzing deformation generated by inflating the tire, or attaching the tire to the wheel. The deformation to be analyzed is analyzed, and the deformation generated in the tire due to the change with time is analyzed. Deformation that occurs in the tire due to changes over time includes deformation of the tire caused by traveling for a set distance, that is, deformation of the tire caused by running growth, deformation due to aging deterioration, deformation of the tire caused by running conditions, and the like. Here, the analysis unit 52c deforms when the tire is incorporated into the rim in the embodiment described later, inflates the tire, that is, deforms caused by filling the tire with a predetermined internal pressure, and causes the tire to travel and grow. Calculate the deformation that occurs in.

  The evaluation value calculation unit 52d calculates the growth amount of the surface of the tire model based on the tire model of the analysis model deformed and analyzed by the analysis unit 52c, and calculates an evaluation value from the calculated growth amount. The evaluation value calculation unit 52d calculates the growth amount by comparing the tire model before deformation analysis with the tire model after deformation analysis. Specifically, the evaluation value calculation unit 52d calculates a distance between an arbitrary element of the tire model before deformation analysis and the same element as the arbitrary element of the tire model after deformation analysis, that is, a coordinate difference, The coordinate difference is calculated as the growth amount. The evaluation value calculation unit 52d calculates a growth amount and an evaluation value for each element on the tire surface (tire profile). Next, the evaluation value calculation unit 52d calculates the average and variance of the calculated growth amounts as evaluation values. Here, the evaluation value calculation unit 52d divides the tire model into a plurality of regions, and calculates the average and variance of the calculated growth amounts for each of the divided regions. After calculating the average and variance of the growth amount for each region, the evaluation value calculation unit 52d, based on the average and variance of the growth amount for each region, the average and variance of the growth amount for each region, that is, Calculate the average and variance of the entire tire.

  The determination unit 52e evaluates the performance of the tire based on the average and variance of the entire tire calculated by the evaluation value calculation unit 52d. The determination unit 52e determines whether the calculated evaluation value satisfies the convergence condition set by the condition setting unit 52b. If the determination unit 52e determines that the calculated evaluation value does not satisfy the convergence condition set by the condition setting unit 52b, the condition setting unit 52b changes the design variable and causes the evaluation value to be calculated again. . Further, when the determination unit 52e determines that the calculated evaluation value satisfies the convergence condition set by the condition setting unit 52b, the determination unit 52e calculates a design variable when the evaluation value is calculated as a calculation result.

  The model creation unit 52a, the condition setting unit 52b, the analysis unit 52c, the evaluation value calculation unit 52d, and the determination unit 52e calculate and determine the analysis model, the condition, and the analysis result, and then store the determined results in the storage unit 54. Stored in a predetermined area. Further, each unit performs analysis and creation using each result stored in the storage unit 54.

  The processing unit 52 includes, for example, a memory and a CPU (Central Processing Unit). At the time of analysis, based on the analysis model created by the model creation unit 52a, input data, and the like, the processing unit 52 reads the program into a memory incorporated in the processing unit 52 and performs computation. At that time, the processing unit 52 appropriately stores a numerical value in the middle of the calculation in the storage unit 54, and extracts the numerical value stored in the storage unit 54 and advances the calculation. The processing unit 52 may realize the function by dedicated hardware instead of the computer program.

  The display unit 55 is a display device such as a liquid crystal display device. The storage unit 54 may be in another device (for example, a database server). For example, the analysis device 50 may access the processing unit 52 and the storage unit 54 by communication from a terminal device including the input / output device 51.

  In such a configuration, the processing unit 52 creates an analysis model by the model creation unit 52a. The model creation unit 52 a stores the created analysis model in a predetermined area of the storage unit 54. Specifically, an analysis model including a tire model to be analyzed is created. Here, the analysis model is a model used by a computer to perform deformation analysis and rigidity analysis using a numerical analysis method such as a finite element method (FEM) or a finite difference method (FDM). It can be analyzed by a computer. The analysis model includes a mathematical model and a mathematical discretization model.

  3A to 3C are diagrams illustrating the land region 4 and the groove wall region 2. FIG. 3A is a perspective view showing an example of the land region 4 and the groove wall region 2. As shown in FIG. 3A, the tread portion 33 includes a land portion 41 and a land portion 42. FIG. 3B is a perspective view illustrating an example of a cross section of the land portion 41. As shown in FIG. 3B, the land portion 41 can be divided into a land portion region 4 and a groove wall region 2.

  FIG. 3C is a diagram illustrating an example of a cross section of the groove wall region 2. As shown in FIG. 3C, the tread portion 33 includes a plurality of land portion regions 4 and a groove wall region 2 provided between the plurality of land portion regions 4. The groove bottom side of the groove wall region 2 is a curved surface having a radius R and continues to the groove bottom surface.

  As shown in FIGS. 3A to 3C, the model creation unit 52a divides the land portion 41 into the land portion region 4 and the groove wall region 2, and separately creates a mesh for the land portion region 4 and the groove wall region 2. To do. The land region 4 as the first region is obtained by penetrating an arbitrary surface such as a surface or a cut surface in a direction orthogonal to the one surface. Of the land portion 41, a portion other than the land portion region 4 becomes the groove wall region 2 which is the second region. The model creation unit 52a automatically generates a mesh for the land region 4 by moving the surface element 40 in the tire radial direction and dividing it into a plurality of parts, for example, by the function of CAD software. The surface element 40 is a part including a surface in contact with the road surface in the land region 4.

  For the groove wall region 2, the model creation unit 52 a automatically generates a mesh by, for example, a CAD software function by moving the cut surface element 20 in the tire circumferential direction or the tire width direction and dividing it into a plurality of parts. The cut surface element 20 is a portion of the land portion 41 excluding the land portion region 4 in the cross section orthogonal to the surface element 40. The groove wall region 2 includes a main groove having a groove wall and a groove bottom shape, a lug groove, a sipe, and a shoulder portion. As for the land region 4 shown in FIG. 3B, a mesh can be generated by dividing the surface element 40 into a plurality of parts while moving the surface element 40 in the tire radial direction without changing the size. FIG. 3D is a diagram illustrating a case where the surface element 40 is moved in the tire radial direction without changing the size of the surface element 40. A mesh is generated by dividing the land region 4 into a plurality while moving the surface element 40 in the tire radial direction. At this time, as shown in FIG. 3D, the surface element 40 is moved in the radial direction without changing the size thereof, so that the position of the center of gravity G does not change in plan view.

The model creation unit 52a may generate a mesh by dividing the land portion region 4 into a plurality of portions by moving in the tire radial direction while changing the size of the surface element 40. FIG. 3E is a diagram showing a case of moving in the tire radial direction while changing the size of the surface element. As shown in FIG. 3E, a surface element 40Z _0, moving from the position Z ₀ of the surface while changing its magnitude in the tire radial direction. At this time, it is moved in the tire radial direction so that the position of the center of gravity in plan view does not change. That is, the position of the center of gravity GZ ₀ surface element 40Z ₀ at the position _{Z 0} of the surface, and the position of the center of gravity GZ ₁ element 40Z ₁ at the position _{Z 1} of the way of movement is the same in plan view. Therefore, each side of the surface element 40Z ₀ which varies at the same ratio, which is similar to the movement middle element 40Z ₁ and the surface element 40Z _0. Similarly, the cut surface element 20 may be moved in the tire circumferential direction without changing its size, or may be moved in the tire circumferential direction while changing its size.

  FIG. 4A is a diagram showing the relationship between the surface element 40 in the land region 4 and the cut surface element 20 in the groove wall region 2. As shown to FIG. 4A, in this embodiment, the surface element 40 of the land part area | region 4 and the cut surface element 20 of the groove wall area | region 2 are each created. The surface element 40 is a two-dimensional element that appears on the tread surface of the land region 4. The cut surface element 20 is a two-dimensional element that appears on the virtual cut surface of the groove wall region 2.

  A mesh can be automatically generated for the land region 4 by moving the surface element 40 in the tire radial direction as indicated by the arrow Y1 and dividing the land region 4 into a plurality of regions. Further, the mesh can be automatically generated for the groove wall region 2 by moving the cut surface element 20 in the tire circumferential direction as indicated by the arrow Y2 and dividing the groove wall region 2 into a plurality of portions. In addition, in FIG. 4A, about the land part area | region 4, instead of the surface element 40, the cut surface element orthogonal to the surface element 40 may be created, and you may make it move to a tire circumferential direction or a tire width direction.

  FIG. 4B is a diagram illustrating an example of a mesh generated for the land portion 41. As shown in FIG. 4B, a model relating to the entire land portion 41 can be obtained by combining the mesh generated for the land portion region 4 and the mesh generated for the groove wall region 2. Similarly, the land portion 42 shown in FIG. 3A can be similarly divided into the land portion region 4 and the groove wall region 2 to process the land portion 42 as a model.

  FIG. 4C is a diagram illustrating an example of a model related to the entire tire. As shown in FIG. 4C, a model relating to the entire tire can be obtained by continuously forming the model relating to the land portion 41 and the model relating to the land portion 42 obtained in the tire circumferential direction as shown in FIG. 4B. it can.

  FIG. 5 is a flowchart showing a tire pattern model creation method according to the first embodiment. As shown in FIG. 5, first, the pattern shape is divided into the land region 4 and the groove wall region 2 (step S101). At this time, with respect to the land portion 41 that is a part of the tire tread surface, the land portion region 4 that is a first region in which any one surface is penetrated in a first direction orthogonal to the one surface, and other than the first region And a groove wall region 2 which is a second region which is a portion of

  Next, a two-dimensional element of the surface or cut surface of the land region 4 is created, and the land region 4 is divided into a plurality while moving the surface element 40 or the cut surface element to at least the groove bottom along the tire radial direction. Thus, a three-dimensional model is generated (step S102). Furthermore, a two-dimensional element of the cut surface of the groove wall region 2 is created, and the groove wall region 2 is divided into a plurality while moving the cut surface element 20 in the tire circumferential direction or the tire width direction along the contour of the land portion. Thus, a three-dimensional model is generated (step S103).

  Then, the three-dimensional model of the land region created in step S102 and the three-dimensional model of the groove wall region created in step S103 are combined and developed in the tire circumferential direction (step S104). That is, a model combining a three-dimensional model of the land region and a three-dimensional model of the groove wall region is continuously formed in the tire circumferential direction.

  With the above processing, the mesh can be automatically generated instead of manually, so that the time for obtaining a model based on a set of elements divided by the mesh can be shortened.

(Division example of groove wall area and land area)
FIG. 6 is a diagram illustrating an example of dividing the groove wall region 2 and the land portion region 4. As shown in FIG. 6, the land portion 41 a is a region sandwiched between the two circumferential main grooves 21 and the two open sipes 61. The open sipe 61 is a sipe whose both ends are open to the circumferential main groove 21.

  An edge sipe 62 is provided in the land portion 41a. The edge sipe 62 is a sipe having one end opened to the circumferential main groove 21 and the other end closed.

  A close sipe 63 is provided in the land portion 41a. The closed sipe 63 is a sipe in which both ends are closed without opening to the circumferential main groove 21.

  The open sipe 61, the edge sipe 62, and the closed sipe 63 are included in the groove wall region 2.

  The land portion region 4 is a region obtained by removing the groove wall region 2 from the land portion 41a. By moving the surface element 40 of the land region 4 in the tire radial direction, a mesh can be automatically generated for the land region 4. Moreover, a mesh can be automatically generated for the groove wall region 2 by moving the cut surface element 20 of the groove wall region 2 in the tire circumferential direction.

  The shape of the shoulder portion may be different from the shape shown in FIG. 7A and 7B are diagrams showing another example of division of the groove wall region 2 and the land portion region 4.

  FIG. 7A shows a case where the shoulder portion 42a is of the SCG (Stress Wear Control Groove) type. A groove M1 is provided in the shoulder portion 42a. For this reason, it is difficult to automatically generate a mesh for the entire shoulder portion 42a. Therefore, as shown in FIG. 7A, the shoulder portion 42a is divided into a land portion region 4 and a groove wall region 2 by a dividing line Da. As for the land region 4, the mesh can be automatically generated by moving the surface element, that is, the mesh on the surface in the tire radial direction. About the groove wall area | region 2, a mesh can be automatically produced | generated by moving a cut surface element, ie, the mesh of a cut surface, in a tire peripheral direction.

  FIG. 7B shows a case where the shoulder portion 42b is a SER (Shoulder Edge Rib) type. As shown in FIG. 7B, a groove M2 is provided. For this reason, it is difficult to automatically generate a mesh for the entire shoulder portion 42b. Therefore, as shown in FIG. 7B, the shoulder portion 42b is divided into the land region 4 and the groove wall region 2 by the dividing line Db. As for the land region 4, the mesh can be automatically generated by moving the surface element, that is, the mesh on the surface in the tire radial direction. About the groove wall area | region 2, a mesh can be automatically produced | generated by moving a cut surface element, ie, the mesh of a cut surface, in a tire peripheral direction.

  As described above, in the tire pattern model creation method according to the first embodiment, for a land portion that is a part of the tire tread surface, an arbitrary one surface is penetrated in a first direction orthogonal to the one surface. Dividing the region into one region and a second region other than the first region, and moving the mesh for the one surface in the first direction to divide the first region into a plurality of regions. Generating a mesh for the first region to generate a three-dimensional model of the first region; and moving the mesh for the cut surface of the second region in a second direction different from the first direction. Generating a mesh for the second region by dividing the second region into a plurality of regions to generate a three-dimensional model of the second region, a three-dimensional model generated for the first region, and the first Comprising the steps of: combining the three-dimensional model generated for the region. This eliminates the need to manually generate the mesh, and can greatly reduce the time for creating the pattern model.

(Second Embodiment)
The groove wall angle of the groove wall region 2 may vary depending on the location. In such a case, the three-dimensional model is generated by dividing the groove wall region 2 and moving the divided parts.

  FIG. 8 is a diagram for explaining a tire pattern model creation method according to the second embodiment. FIG. 8 shows a case where the groove wall angle θ of the groove wall region 2 changes. The groove wall angle θ is an angle formed between the side surface 4S of the land region 4 and the wall surface 2S of the groove wall region 2.

  As shown in FIG. 8, in the case where the land portion 41 b is composed of the land portion region 4 and the groove wall region 2, the representative position A, the representative position B, and the representative position are formed at the end of the surface element 40 of the land portion region 4. Position C and representative position D are set. In the representative position A, the representative position B, the representative position C, and the representative position D, the groove wall angle θ is 10 degrees between the representative position A and the representative position B, and the groove wall angle is between the representative position B and the representative position C. It is assumed that θ is 8 degrees, and the groove wall angle θ is 12 degrees between the representative position C and the representative position D. By dividing the groove wall region 2 into partial regions at the same angle, a mesh can be automatically generated for each partial region.

  FIG. 9 is a diagram illustrating an example of a cut surface element at each representative position. FIG. 10 is a diagram illustrating an example of a model of the groove wall region 2 obtained by moving each cutting plane element at each representative position.

  In FIG. 9, the cut surface element 20A between the representative position A and the representative position B, the cut surface element 20B between the representative position B and the representative position C, and the cut surface element between the representative position C and the representative position D. A mesh is created while moving 20C in the direction of arrow YA, the direction of arrow YB, and the direction of arrow YC, respectively. In this way, the groove wall region 2 is divided into partial regions at the same angle, and a mesh is created by dividing the partial region into a plurality of parts while moving the elements of the partial region, that is, the mesh. As shown, a model of groove wall region 2 is obtained.

  FIG. 11 is a diagram for explaining representative positions. FIG. 11 shows the periphery of the land portion 41b in plan view. As shown in FIG. 11, the positions P1, P2, P3, and P4 at which the groove wall angle changes are preferably set as the representative positions. For example, it is preferable to set the position of the apex where the groove wall angle changes as the representative position. In some cases, a mesh of each cutting plane element may be created with the same node and the same number of elements.

  FIG. 12 is a diagram illustrating an example of a model of the land portion 41b obtained by the second embodiment. As described above, by dividing the land region 4 and the groove wall region 2 to create a mesh for the land region 4, and further dividing the groove wall region 2 for each groove wall angle to create a mesh. A model of the land portion 41b shown in FIG. 12 can be obtained.

  FIG. 13 is a flowchart showing a tire pattern model creation method according to the second embodiment. In the second embodiment, step S103 in FIG. 5 is replaced with step S204 from step S201 shown in FIG. 13 to obtain a three-dimensional model of the land portion.

  As shown in FIG. 13, first, the pattern shape is divided into the land region 4 and the groove wall region 2 (step S101). Next, a two-dimensional element of the surface or cut surface of the land region 4 is created, and the surface element 40 or the cut surface element is moved to at least the groove bottom along the tire radial direction and divided into a plurality of three-dimensional elements. A model is generated (step S102).

  For the groove wall region 2, first, at least one groove wall angle representative position is selected by changing the groove wall angle (step S201). A mesh is created for each cut surface element of the groove wall region at each representative position (step S202).

  Next, a three-dimensional model of each groove wall partial region is generated by creating a mesh by dividing the groove wall region into a plurality of portions while moving each cut surface element along the contour of the land portion (step S203). ). A three-dimensional model of the groove wall region is obtained by combining and integrating the models of the groove wall partial region (step S204).

  Finally, the three-dimensional model of the land region created in step S102 and the three-dimensional model of the groove wall region created in step S203 are combined and developed in the tire circumferential direction (step S104).

  By dividing the groove wall area into a number of partial areas, meshes can be generated automatically, not manually, even for complex areas where the curved surfaces of the groove bottoms intersect. The time to obtain can be reduced.

(Third embodiment)
By the way, the case where the groove wall angle θ of the groove wall region 2 is zero is also considered. In that case, since the cut surface element of the groove wall region 2 cannot be created, it is difficult to create a mesh by moving the cut surface element. Therefore, in the third embodiment, the cut surface element of the groove wall region 2 can be created by extending the cut surface element of the groove wall region 2 to the inside of the land portion region 4. Thereby, even if groove wall angle (theta) is zero, a cut surface element can be moved and a groove wall area | region 2 can be divided | segmented into plurality, and a mesh can be created.

FIG. 14A is a diagram illustrating a tire pattern model creation method according to the third embodiment. 14B is a diagram showing an example of the cutting surface elements 20 ₁ which gave thick. 14C is a diagram showing an example of a land area _{4 1} except the cut surface element 20 ₁ shown in FIG. 14B.

As shown in FIG. 14A, the land portion 41c includes a land region _{4 1} and the groove wall region _{2 1.} Cut surface elements 20 ₁ of the groove wall region 2 ₁ has a shape obtained by extending the inner side of the land area 4 ₁ from the cutting surface elements 20 shown in FIG. In this embodiment, the inner three elements partial extended shape of the upper surface of the land portion 41c, to have a thickness on the cut surface element 20 _1.

Specifically, the representative position A of each groove wall angle shown in FIG. 14A, B, C, D, from E ..., the corresponding position A ₁ at a distance of at least one element h inside the land area 4 _1, B ₁ , C ₁ , D ₁ , E ₁ ... Are set. That is, the distance between the representative positions A, B, C, D, E... And the corresponding positions A ₁ , B ₁ , C ₁ , D ₁ , E ₁ . Then, these corresponding positions A ₁ , B ₁ , C ₁ , D ₁ , E ₁ ... Are divided into a groove wall area and a land area.

With such the cut surface elements 20 ₁ which gave the thickness to generate a mesh, for example, as shown in FIG. 14B, the cutting surface elements 20 ₁ through the representative position A and the corresponding position A ₁ is obtained. By moving the cut surface elements 20 _1, the groove wall angle can be created automatically meshes be zero.

Because of slightly thickened cutting surface elements 20 _1, as shown in FIG. 14C, the land area 4 ₁ decreases by the amount of its thickness. The land area 4 _1, by dividing the surface element 40 ₁ in a plurality is moved in the tire radial direction, it can automatically generate meshes. At this time, as described with reference to FIG. 3E, it may be moved in the radial direction of the tire while changing the size of the surface element 40 _1.

  FIG. 15 is a flowchart showing a tire pattern model creation method according to the third embodiment. In the third embodiment, the cut surface element of the groove wall region is given a thickness by inserting the process of step S300 between step S201 and step S202 of FIG.

As shown in FIG. 15, first, it divided into a land area _{4 1} and the groove wall region _{2 1} (step S101). The groove walls region 2 _1, first, to select a representative position of the at least one groove wall angle due to the change in the groove wall angle (step S201). Then, set the corresponding position on the inner side of the land portion surfaces of the representative position of the groove wall angle, to have at least one element thickness on the cut surface element groove wall region 2 ₁ (step S300). A mesh is created for each cut surface element of the groove wall region at each representative position (step S202).

  Next, a three-dimensional model of each groove wall partial region is generated by creating a mesh by dividing each groove wall partial region into a plurality while moving each cut surface element along the contour of the land ( Step S203). A three-dimensional model of the groove wall region is obtained by combining and integrating the models of the groove wall partial region (step S204).

  By creating a two-dimensional element of the surface or cut surface of the land region 4 and moving the surface element 40 or the cut surface element to at least the groove bottom along the tire radial direction to divide the land region 4 into a plurality of parts, A three-dimensional model is generated (step S102). Finally, the three-dimensional model of the groove wall region created in step S203 and the three-dimensional model of the land region created in step S102 are combined and developed in the tire circumferential direction (step S104).

As above, in the present embodiment, when dividing the land portion 41c in the groove walls region 2 ₁ a land region 4 ₁ and the second region is a first region, to set the representative position of the groove wall angle and setting at least one element apart position corresponding to the inner direction of the land portion 41c from the representative positions, it is divided into a land area 4 ₁ and the groove wall region 2 ₁ along the corresponding position. Accordingly, even when it is difficult to move the cut surface along the contour of the land portion because the groove wall angle θ is zero, the groove wall region 2 can be formed by providing a thickness of one or more elements. _A cutting plane element can be generated for one.

(Fourth embodiment)
When combining the three-dimensional model of the land region 4 and the three-dimensional model of the groove wall region 2, the land portion 4 and the groove wall region 2 are arranged so that the mesh shapes of the adjacent regions coincide with each other. It is desirable to generate a mesh of region 4 and groove wall region 2. That is, in the model of the land portion 41b shown in FIG. .

  If a mesh is created in this way, node sharing between each region boundary can be used, so that setting work such as constraint coupling is not required, and the efficiency of creating an analysis model can be further improved. Note that the constrained coupling is to constrain the relative displacement between different region nodes at the contour boundary of the adjacent region.

(Tire simulation method)
Next, a tire simulation method according to this embodiment will be described. Note that the tire simulation method according to the present embodiment can be realized by the analysis device 50 described above.

  FIG. 16A and FIG. 16B are diagrams for explaining a method of creating the entire tire model 24 by integrating the pattern model 22 and the casing model 23.

  As shown in FIG. 16A, in addition to the pattern model 22 created as described above, a casing model 23 that is a part other than the pattern model 22 is created in advance. Then, by integrating the created pattern model 22 with the casing model 23, as shown in FIG. 16B, a model 24 of the entire tire can be created. Here, the term “integration” means that the respective regions are completely coupled in the form of node sharing or constrained coupling at the contour boundary of each adjacent region.

  The tire characteristics can be simulated by setting analysis conditions using the created model 24 of the entire tire. For example, tire characteristics can be simulated by giving predetermined fitting conditions, air pressure conditions, load conditions, and the like as analysis conditions to the model 24 of the entire tire.

  FIG. 17 is a flowchart illustrating an example of a method for creating and simulating the model 24 of the entire tire. As shown in FIG. 17, the casing model 23 is created in advance by the model creation unit 52a (step S301). Next, the tire pattern model 22 is created by the model creation unit 52a (step S302). And the tire whole model 24 is produced | generated by integrating the pattern model 22 and the casing model 23 (step S303). In addition, the order of creation of the casing model 23 (step S301) and creation of the pattern model 22 (step S302) is not limited.

  Next, an analysis condition is set by the condition setting unit 52b (step S304). Based on the set analysis conditions, the analysis unit 52c performs simulation on tire characteristics (step S305). In addition, about the result of simulation, the evaluation value calculation part 52d calculates, and the determination part 52e performs determination.

  As described above, a mesh is created for each of the pattern and the casing, the pattern model 22 and the casing model 23 are obtained, and the two are integrated, so that a fine mesh is used only for the groove bottom where strain concentration is likely to occur. be able to. Thereby, the scale (number of elements) of the analysis model can be reduced. As a result, the efficiency of creating the entire tire model 24 can be further improved, and the analysis time can be shortened. Therefore, it is possible to reduce the time required to generate a mesh and obtain a model based on a set of elements divided by the mesh, thereby reducing the time required for simulation.

(Example)
FIG. 18 is a diagram illustrating an example of a tire pattern analysis model. In the Examples, the conventional method of manually generating a mesh and the respective embodiments were evaluated for the shortening of the creation time of the tire pattern analysis model. In this example, the tire pattern analysis model creation time shown in FIG. 18 was evaluated. The tire pattern analysis model shown in FIG. 18 is a pattern model 22 of an off-the-road tire with a tire size of 27.00R49 RB42.

  Table 1 shows the time for creating a pattern model of 900,000 pixels as “100” in the case of the conventional method, and shows the case of the above embodiments as an index.

  As shown in Table 1, the time for creating the pattern model is “30” in the first embodiment, “20” in the second embodiment, “20” in the third embodiment, In the case of the fourth embodiment, it is “15”, and it has been found that the pattern model can be created in a shorter time than in the case of the conventional method in any of the embodiments.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Groove wall area | region 2S Wall surface 4 Land area | region 4S Side surface 11 Bead core 12 Bead filler 13 Carcass layer 14 Belt layer 15 Tread rubber 16 Side wall rubber 20, 20A, 20B, 20C Cutting surface element 21 Circumferential main groove 22 Pattern model 23 Casing model 24 Entire tire model 33 Tread portion 40 Surface elements 41, 41a, 41b, 41c, 42 Land portions 42a, 42b Shoulder portion 50 Analysis device 51 Input / output device 52 Processing portion 52a Model creation portion 52b Condition setting portion 52c Analysis unit 52d Evaluation value calculation unit 52e Determination unit 53 Input unit 54 Storage unit 55 Display unit 60A, 60B Lug groove 61 Open sipe 62 Edge sipe 63 Close sipe 141 High angle belt 142, 143 Cross belt 144 Belt cover 145 Circumferential reinforcing layer L tire equatorial plane _G, GZ _0, GZ ₁ centroid M1, M2 groove θ groove wall angle

Claims (5)

About the land part which is a part of a tire tread surface, the 1st field which penetrated arbitrary one surface in the 1st direction perpendicular to the one surface, and the 2nd field which is a part other than the 1st field A step of dividing;
Generating a mesh for the first region by moving the mesh for the one surface in the first direction to divide the first region into a plurality of regions, and generating a three-dimensional model of the first region; ,
The mesh on the cut surface of the second region is moved in a second direction different from the first direction to divide the second region into a plurality of pieces to generate a mesh for the second region and Generating a three-dimensional model of two regions;
Combining the three-dimensional model generated for the first region and the three-dimensional model generated for the second region.   When generating a three-dimensional model of the second region, when the groove wall angle formed between the side surface of the first region and the wall surface of the second region changes, the second region is divided into portions where the groove wall angle is the same. And generating a three-dimensional model by generating a mesh for the second region while moving the cutting plane in the second direction for each of the divided portions, and combining the three-dimensional models of the individual groove wall partial regions The tire pattern model creation method according to claim 1, wherein a three-dimensional model of the second region is generated.   When dividing the land portion into the first region and the second region, a representative position of the groove wall angle is set, and at least one element is separated from the representative position in the inward direction of the land portion. The tire pattern model creation method according to claim 2, wherein a position is set, and the first area and the second area are divided along the corresponding position.   When combining the three-dimensional model generated for the first region and the three-dimensional model generated for the second region, the meshes of the first region and the second region are matched so that the shapes of the meshes of adjacent regions match. The tire pattern model creation method according to any one of claims 1 to 3, wherein the tire pattern model is generated. Creating a tire pattern model with the tire pattern model creating method according to any one of claims 1 to 4,
Creating a casing model that is a three-dimensional model for portions other than the tire pattern model;
Integrating the tire pattern model and the casing model;
A tire simulation method including a step of performing simulation on a model of the entire tire obtained by integrating the tire pattern model and the casing model.

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